Kevin Spacey joins 'Horrible Bosses' cast

Kevin Spacey has come aboard "Horrible Bosses," filling in the final piece of New Line's movie's casting puzzle as the workplace murder comedy chugs toward a July 6 start in Los Angeles.

"Bosses," which is being directed by Seth Gordon, centers on three best friends who, frustrated by their jobs, come to the conclusion the only solution is to kill one another's bosses.

The project has been in development for years at New Line, and in May finally nailed down its three leads: Jason Bateman, Charlie Day and Jason Sudiekis.

But while Warner Bros, the parent company of New Line, has success in breaking actors to a larger stage with "The Hangover," it felt the project needed A-listers to shore it up.

This is why it brought onboard Colin Farrell and Jennifer Aniston as two of the three bosses, and Jamie Foxx as a scam artist.

The final part was that of Bateman's boss, a master manipulator with an attractive wife. The role is described as meaty and integral to the movie and New Line was in talks with several names, including Tom Cruise, Philip Seymour Hoffman and Jeff Bridges, before nabbing Spacey.

Spacey, repped by CAA and Joanne Horowitz, has "Casino Jack" in the can and is shooting the ensemble Wall Street thriller "Margin Call." He is also the artistic director of the Old Vic Theatre Company.